Flexible pipeline pigs

ABSTRACT

A flexible pipeline pig adapted for removing liquids and debris from pipelines. The pig includes at least one plug having a deformable peripheral wall formed of resilient material. The wall defines a peripheral surface which establishes a movable seal with the adjacently surrounding portion of the inner cylindrical wall of the pipe. An arcuate channel defined by the pipe&#39;&#39;s inner cylindrical wall, on one side, and a spiral groove in the outer peripheral wall of the plug, on the other side, establishes fluid communication between the upstream and downstream sections of the pipeline. Through the fluid communication channel is controllably routed a fraction of the pig-propelling fluid which sweeps the pipe&#39;&#39;s inner wall between the ends of the pig as it moves through the pipeline. The liquids and debris which exist in said channel or on said portion of the pipe&#39;&#39;s inner cylindrical wall are cleared through said channel and discharged downstream in front of the pig.

United States Patent Powers 1451 May 2, 1972 [54] FLEXIBLE PIPELINE PIGS Marvin D. Powers, 6060 Skyline Drive, Apt. 14, Houston, Tex. 77027 22 Filed: Apr. 6,1970

21 Appl.No.: 25,998

[72] Inventor:

52 us. 01. ..15/l04.06 R 51 1m. 01 ..B08b 9/04 58 Field of Search ..15/3.5, 104.06 R, 104.06A

[56] References Cited UNITED STATES PATENTS l,7l3,895. 5/1929 Ford ..15/104.06 R 3,530,523 9/1970 Ver Nooy... .....l5/104.06 R 2,188,959 2/1940 Schaer ..l5/l04.06 R

Primary Examiner-Edward L. Roberts Attorney-Michael P. Breston [5 7] ABSTRACT A flexible pipeline pig adapted for removing liquids and debris from pipelines. The pig includes at least one plug having a deformable peripheral wall formed of resilient material. The wall defines a peripheral surface which establishes a movable seal with the adjacently surrounding portion of the inner cylindrical wall of the pipe. An arcuate channel defined by the pipes inner cylindrical wall, on one side, and a spiral groove in the outer peripheral wall of the plug, on the other side,

establishes fluid communication between the upstream and downstream sections of the pipeline. Through the fluid communication channel is controllably routed a fraction of the pig-propelling fluid which sweeps the pipes inner wall between the ends of the pig as it moves through the pipeline. The liquids and debris which exist in said channel or on said portion of the pipes inner cylindrical wall are cleared through said channel and discharged downstream in front of the pig.

7 Claims, 12 Drawing Figures v PATENTEDMAY 2 I972] 3, 659 305 I 'SHEETIUFG INVENTOR.

A TTORNEY MARVIN D. PowERs PATENTEBNAY 2 I972 3. 659, 305

K a i.

I F L7 5- INVENTOR.

A TTORNE Y MARVIN Ii Pan/5P5 PATENTEDMY 21972 3,659,305 SHEET 3 CF 3 MA RVIN D. POWERS IN VEN'TOR.

ATTORNEY FLEXIBLE PIPELINE PIGS BACKGROUND OF THE INVENTION Various pipeline pigs are known in the art. One such pig includes a plug made of a flexible material. A fluid under pressure propels the pig through the pipeline. The resilience of the pigs material maintains a sealing but slidable engagement between the outer peripheral surface of the plug and the inner cylindrical surface of the adjacent pipe.

When new pipelines are tested they are frequently subjected to a hydrostatic test. After such test it is desired that the pipeline be cleared of liquids before hydrocarbon fluids are sent therethrough. When hydrocarbon fluids such as combustible gases, oils, gasolines, etc., are sent through an improperly dehydrated pipeline, they are likely to become rejected by the consumer for containing an excessive amount of moisture. As a result, pipeline operators spend considerable effort in making certain that substantially all of the liquids in the pipeline are cleared and the pipes walls are dry, prior to allowing the pipeline to carry such hydrocarbon products.

When using the above-described known pig, several passes through the pipeline must be made by the pig with the expectation that each such pass will remove a portion of the still remaining liquid in the pipeline.

But even after a great number of passes with such a conventional pig, there still is no assurance that substantially all of the liquids have been removed from the pipeline. Pockets and/or films of liquids frequently remain in certain sections of the pipeline and their existence manifests itself only after the hydrocarbon products are analyzed for their moisture content.

SUMMARY OF THE INVENTION This invention provides a pipeline pig having at least one plug which includes a deformable peripheral wall of resilient material. The wall provides a movable seal with the adjacently surrounding portion of the pipes inner cylindrical wall. At least one arcuate channel in the pigs outer peripheral wall bounded on one side by the pipes inner cylindrical wall allows the upstream section to fluidly communicate with the downstream section of the pipeline. The fraction of the pigpropelling fluid flowing through this channel effectively clears and removes any liquids which may exist in the arcuate channel.

The channels longitudinal configuration may include portions which are spiraling, annular, rectilinear, etc. A solid or flexible holl'ow shaft may longitudinally extend through at least a portion of the pig s body. A transverse partition in the shaft prevents direct fluid communication between the rear and front ends of the pig and diverts the fluid flow through said channel. The pig may also be advantageously provided with directional fluid discharge means which produce a stir ring effect in front of the moving plug. This stirring effect facilitates the removal of debris existing in the downstream section of the pipeline.

Accordingly, it is a main object ,of this invention to provide new and improved flexible pigs which are especially effective in removing liquids and debris from the walls of a pipeline, which are relatively inexpensive to manufacture, and which considerably reduce the time and effort required to clear liquids and debris from pipelines.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 through 4 show the improved pig of this invention with fluid channels of varying configurations;

FIG. Sis a view in cross-section on line 5--5 in FIG. 1; v

FIG. 6 is a view in cross-section of the pig with discharge nozzles;

FIG. 7 is a front view on line 77 in FIG. 6;

FIG. 8 is a view in cross-section of the pig with a conical discharge head;

FIG. 9 is a perspective view of the conical discharge head in FIG. 8;

FIG. 10 is a view in cross-section of the pig with a solid center shaft hollow on both ends; and

FIGS. 11 and 12 show a pig similar to that of FIG. 10 with a flexible hollow center shaft.

This invention will be illustrated in connection with preferred embodiments. For ease of understanding, the same numerals are used to designate similar parts.

Referring now to the drawings, the pig or plug is generally designated as 10 and is especially effective for clearing liquids in front of pig 10, as well as from the inner wall 12 of a long pipeline 14, Pig 10 is propelled through pipeline 14 by a pressurized fluid 16, typically a gas under high pressure, applied from the upstream section 18 of pipeline 14. At any instant of time, pig l0 seals off an annular area I9 of pipeline [4 between the upstream section 18 and the downstream section 22. As pig 10 becomes propelled through the pipeline, the sealed-off area 19 moves with pig 10. Any pool of water 20 which may accumulate in front of the moving pig 10 will be pushed to a downstream outlet (not shown).

It will be appreciated that a small portion of the liquid from pool 20 will bypass the front wall 24 of the main body 26 of pig l0 and enter the sealed-off annular area 19 between the peripheral surface 28 of body 26 and the inner cylindrical wall 12 of the pipe between the ends of pig 10. Also, especially with very long pipelines extending through hilly terrains, pipeline 14 may have many turns in both lateral and vertical directions. Such'curvilinear pipelines frequently include certain cross-sectional irregularities which tend to form pockets which allow liquids to accumulate therein.

Body 26 is typically made of a flexible material which offers a resistance to movement due to the frictional drag between its peripheral surface 28 and the inside wall 12 of pipeline 14. Accordingly, a pressure differential across the plug 10 is established as it is being propelled through'the pipeline, with the greater pressure being exerted against the rear wall 30 of body 26. I

As thus far described, pig 10 is conventional and operates in a known manner. Several passes through the pipeline 14 by pig 10 are required in order to clear the liquids from pipeline 14 and to sufficiently dry its inner cylindrical wall 12. v

In accordance with this invention, in order to continuously remove the liquids which may bypass the front wall 24 and penetrate into the sealed-off annular area 19 and/or which may be trapped in certain low-level pockets'in pipeline 14, there is provided on the outer peripheral surface 28 of body 26 an arcuate channel, generally designated as 40, for establishing fluid communication in the direction of fluid flow between the upstream and downstream sections 18 and 22. The channels configuration is not critical as long as it allows an effective cylindrical wiping contact between the fluid flowing through the channel and the inner cylindrical wall 12 of pipeline 14. This wiping contact allows the propelling fluid in channel 40 to sweep the inner wall 12 and to forcibly clear from the sealed-off annular area 19 any liquids existing therein. The liquids in the annular area 19 become absorbed or mixed with the stream of fluid flowing through channel 40 and returned to the front end of the pig.

In the embodiment shown in FIG. 1, channel 40 is defined by an opening 42 in rear wall 30, a longitudinally extending bore 44, a radially extending bore 46 having an opening 48, an opening 50 in front wall 24, a longitudinally extending bore 52, a radially extending bore 54 having an opening 56, and an arcuate channel 60 in the form of a spiral to allow fluid communication between openings 48 and 56. Channel 60 preferably extends 360 around the outer peripheral wall 28 to completely surround the body 26 of pig I0.

In operation of the embodiment shown in FIG. I, a fraction of the pig-propelling fluid 16 will flow through opening 42, bore 44, bore 46, spiral channel 60, bore 54, bore 52, and opening 50. Since the spiral 60 extends at least 360 around the peripheral surface 28, it will be appreciated that the entire surface of the inner cylindrical wall 12 within the annular area 19 will be swept by the stream of fluid flowing through arcuate channel 40. Consequently, any liquids existing within the sealed-off annular area 19 will be absorbed and/or mixed with the fluid stream and discharged through the front opening 50 into the downstream section 22. The discharged liquids together with the liquid pool 20 will subsequently be removed through a downstream outlet (not shown).

In the embodiment of FIG. 2 between bores 44 and 52 are provided two spirals 60 and 60'. Numerals with primes throughout the drawings are intended to designate similar elements, as will be evident from the drawings. While only two spirals 60 and 60 are provided in the embodiment of FIG. 2, more than two such spirals may be provided, if desired.

In FIG. is shown a view in cross-section of the wall 62 forming channel 60. This wall is conveniently 'made of a material stiffer than the material of which flexible body 26 is made. This additional stiffness is desired to prevent channel 60 from collapsing under the pressure of the propelling fluid 16. Similarly, rear wall 30 may also be made ofa stiffer material. This stiffer material is preferably a suitable plastic. Another advantage obtained from wall 62 is that it scrapes the inner cylindrical wall 12 of pipeline 14 to remove water droplets and small debris which may exist in the sealed-off area 19.

Referring now to FIG. 3, the fluid communication channel 40 extends from an opening 72 in the rear wall 30 to an opening 70 in the front wall 24 through a' rectilinear peripheral channel 74, an annular channel 76, and another rectilinear channel 78. The direction of fluid flow through channel 40 is indicated by the arrows 6 1.

In the embodiment of FIG 4, which is similar to the embodiment of FIG. 3, an additional annular channel 76' is provided in parallel with annular channel 76. The operation of the embodiments shown in FIGS. 3 and 4 are in all respects similar to the operation of the embodiments described in connection with FIGS. 1 and 2, and no further description is believed necessary. I

In the embodiment shown in FIG. 6, in bore 52 is inserted a bushing, generally designated as 80, having an inwardly threaded head 82 to which cylinder 84 having an end wall 86 is securely threaded. Extending from cylinder 84, near end wall 86, are pipes 87 having curbed nozzles 88. The orientation of the nozzles 88 is selected to provide a desirable stirring effect to assist in removing debris from the inner wall 12 of the downstream section 22. The arrangement of the pipes 87 is better shown in FIG. 7.

Referring now more specifically to FIGS. 8 and 9, instead of employing discharge pipes 87, a conical discharge head 90, having a conical wall portion 92 and a threaded cylindrical sleeve portion 94, may be provided. Sleeve 94 is threadedly secured to the head 82. Thus, with the embodiment of FIG. 8, the fluids discharge into the downstream sections 22 along a conical surface 92 which is maintained in spaced-apart relation with an adjacent conical surface 96, provided by an extension of head 82, by spacers 93.

In the embodiment shown in FIG. 10, there is provided a solid shaft hollow at both ends, generally designated as 100, which extends longitudinally from the rear wall 30 to the threaded head 80. Shaft 100 includes a transverse wall 102 to prevent direct fluid communication between the upstream and downstream sections 18 and 22.

Fluid flow between the portions 104 and 106 of shaft (through channel 40) is indicated by the arrows 61.

In the embodiment shown in FIG. 11, instead of employing a solid hollowshaft 100, there is now provided a shaft 110 having a flexible corrugated wall 111. A transverse resilient plug 112 inside shaft 110 is held under compression between two plates 114 and 116 secured together by a bolt 118. The advantages of using a flexible shaft 110 instead of shaft 100 will be evident from an inspection of FIGS. 10 and 12 wherein pig 10 is shown traversing a curbed portion of the pipeline 14.

The fluid flowing through arcuate channel 40 in the embodiments of FIGS. 10 and 11 will remove the liquids existing in the annular area 19 in a manner previously described.

It will be apparent that while certain preferred embodiments have been described and illustrated in the drawings, other modifications will readily become apparent to those skilled in the art.

What is claimed is:

l. A pipeline pig for removing liquids from pipelines, said pig comprising:

at least one plug having a resilient member with an outer surface which, in use, engages the inner wall of a pipeline and forms a movable sealing surface therewith,

a groove in said outer surface of said resilient member, said groove including at least an arcuate portion and defining with said inner wall of said pipeline a fluid flow channel, a first bore extending into a portion of the body of said plug from the end facing said upstream section,

a second bore extending into a portion of the body of said plug from the end facing said downstream section, and fluid passage means providing fluid communications between said bores and said channel to enable a portion of a pig-propelling fluid to be supplied through said first bore from the upstream section of the pipeline into said channel, whereby any liquids which are contained on said engaged inner wall of said pipeline become ejected through said second bore into the pipelines downstream section.

2. The pig of claim 1 and further including,

a first hollow shaft in said first bore, and

a second hollow shaftin said second bore.

3. The pig of claim 2 wherein each of said hollow shafts has a flexible outer wall.

4. The pig of claim 1 and further including,

fluid discharge means coupled to said second bore and facing said downstream section.

5. The-pig of claim 4 wherein,

said discharge means include at least onev nozzle for discharging the fluids from said channel into said downstream section.

6. The pig ofclaim 5 wherein,

said nozzle is a conical nozzle.

7. The pig ofclaim 5 wherein,

said nozzle includes at least one radially extending hollow tube. 

1. A pipeline pig for removing liquids from pipelines, said pig comprising: at least one plug having a resilient member with an outer surface which, in use, engages the inner wall of a pipeline and forms a movable sealing surface therewith, a groove in said outer surface of said resilient member, said groove including at least an arcuate portion and defining with said inner wall of said pipeline a fluid flow channel, a first bore extending into a portion of the body of said plug from the end facing said upstream section, a second bore extending into a portion of the body of said plug from the end facing said downstream section, and fluid passage means providing fluid communications between said bores and said channel to enable a portion of a pig-propelling fluid to be supplied through said first bore from the upstream section of the pipeline into said channel, whereby any liquids which are contained on said engaged inner wall of said pipeline become ejected through said second bore into the pipeline''s downstream section.
 2. The pig of claim 1 and further including, a first hollow shaft in said first bore, and a second hollow shaft in said second bore.
 3. The pig of claim 2 wherein each of said hollow shafts has a flexible outer wall.
 4. The pig of claim 1 and further including, fluid discharge means coupled to said second bore and facing said downstream section.
 5. The pig of claim 4 wherein, said discharge means include at least one nozzle for discharging the fluids from said channel into said downstream section.
 6. The pig of claim 5 wherein, said nozzle is a conical nozzle.
 7. The pig of claim 5 wherein, said nozzle includes at least one radially extending hollow tube. 